Foveon Sensor
A sensor that records all three colours at every location by stacking three photodiode layers at different depths in the silicon.
In depth
Because different wavelengths penetrate silicon to different depths, blue can be captured near the surface, green below it and red deepest of all. This removes the need for demosaicing entirely, giving exceptional per-pixel detail and colour accuracy at base ISO. The layered structure is much less efficient, so high-ISO performance has always been poor.
Examples in practice
A Foveon file resolves fine text on a distant sign that a Bayer sensor of the same nominal resolution smears.